1. Field of the Invention
The present invention relates to a communication system, and more particularly to a communication system of a point-to-point connection method under the third party call control.
2. Description of the Related Art
In recent years, the next generation communication networks have been actively examined by communication carriers using the Internet Protocol (IP) technology. This kind of next generation communication networks is called a Next Generation Network (NGN). In the NGN, a method for establishing a session between the server and the client trying to make the communication, and managing a band for each session is often used. Also, in the NGN, a session control protocol for use to secure the band is the Session Initiation Protocol (SIP), for example.
Also, there was disclosed a technique in which when a client device without mounting a band initiation session control protocol communicates over a band security network, a session alternate device establishes a band initiation session within the band security network, instead of the client device (e.g., refer to JP-A-2008-78878).
Also, the Simple Object Access Protocol (SOAP) for exchanging information between the applications is well known.
Also, a 3rd Party Call Control, call control by third party (3PCC) was disclosed in RFC3725, and a REFER method of SIP was disclosed in RFC3515, for example.